1894 - 5 .] Antivencne and Bmyentd Blood-Serum. 469 
without much deterioration of health ; for example, by restricting 
the diet of a herbivorous animal to animal food. 
A number of young white rats, accordingly, were put on an animal 
dietary, as soon as they had been weaned ; and, with the slight 
addition of a little vegetable food once or twice a week, found 
necessary to maintain them in fairly good health, this dietary was 
continued for seven weeks. To one of the rats, a dose of cobra venom 
one-and-a-half times greater than the minimum-lethal was then 
administered by subcutaneous injection, and, although marked 
symptoms of poisoning were produced, the rat recovered. Two 
weeks subsequently, the animal dietary having been continued, 
another of these white rats received twice the minimum-lethal dose, 
and it also recovered after a temporary illness. The experiments 
could not be carried further, as the other members of This family 
had fallen into bad health, and one after the other had died before 
this time. 
In animals whose progenitors had subsisted mainly upon a 
vegetable diet, the conversion of the diet into that of carnivorous 
animals is, therefore, alone sufficient to reduce the vulnerability to 
venom, and to cause, in this respect, an approximation to the 
resistance of a carnivorous animal. 
This fact appears to indicate that the toxic effects of serpents’ 
venom are dependent to a large extent upon an influence on the 
blood, an influence as yet only partially and imperfectly recognised. 
Protection produced by Stomach Administration . — In the experi- 
ments which I have hitherto described, and, indeed, apparently in 
all others made in this new subject of Serum Therapeutics, protec- 
tion has been produced by the subcutaneous or, less frequently, the 
intra-venous injection of the venom or other toxic substance. 
These methods of administration are attended with inconveni- 
ences, which, it seemed possible, might be avoided were the toxic 
substance introduced into the stomach or other part of the 
alimentary canal. Ho doubt, the probability of thus producing 
protection is opposed by the fact, recognised even at the time of 
Celsus, and corroborated by such modern observers as LaQerda, 
Weir Mitchell, Fayrer and Brunton, and Calmette, that serpents’ 
venom is either altogether inert, or nearly so, when it is introduced 
into the stomach or any other part of the alimentary canal, 
